125 



rush of the fragments through the air in the neighbourhood 

 of the observers. 



As to the nature of the matter of which these meteorites 

 are composed, about 24, and those the most common, of the 

 64 elements at present recognised as constituents of the 

 earth's crust have been met with, while no new element has 

 been discovered. The most frequent are Iron, Magnesium, 

 Silicon, Oxygen, and Sulphur ; next follow Aluminium, Cal- 

 cium, Nickel, Carbon and Phosphorus ; while in smaller 

 quantity occur Hydrogen, Nitrogen, Lithium, Sodium, Potas- 

 sium, Titanium, Chromium, Manganese, Cobalt, Copper, 

 Arsenic, Antimony, Tin, and Chlorine. All of these are met 

 with in the combined state, but some, among which may 

 be mentioned Iron Carbon and Sulphur, are present also 

 in the elementary condition. Of the compounds found 

 in meteorites, the following are as yet new to terrestrial 

 mineralogy : — Various alloys of nickel and iron ; Troilite, or 

 ferrous sulphide FeS ; Oldhamite, or calcium sulphide CaS ; 

 Osbornite, a titanium-calcium sulphide; Daubreelite ) a 

 compound analogous to chromite, and having the formula 

 (Fe,Cr) 3 S 4 ; Lawrencite, or ferrous chloride ; Asmanite, a 

 rhombic variety of silica ; Mashelynite, a cubic labradorite dis- 

 covered by Tschermak ; and different varieties of 3chreibersite, 

 containing phosphides of nickel and iron. Of the above, it is 

 held by some that the troilite is identical with some varieties 

 of terrestrial magnetic pyrites, and that the asmanite dis- 

 covered by Maskelyne is the same as the terrestrial tridymite, 

 the optical properties and the crystalline form of which, as 

 then known, were quite different from those observed in 

 asmanite. The other compounds observed in meteorites are found 

 also among terrestrial minerals ; they are, magnetic pyrites, 

 magnetite, chromite, tin oxide, varieties of olivine, bronzite 

 and augite, enstatite, anorthite, and perhaps also labradorite 

 The investigation of the nature of the minerals of which mete- 

 orites are composed has received a great impetus through the 

 work done upon the specimens in this Museum by the late 

 Keeper Professor N. S. Maskelyne with the assistance of Dr. 

 Walter Flight. 



For the purpose of classification meteorites may be con- 

 ic 2 



